Reverse osmosis separation apparatus

ABSTRACT

A reverse osmosis liquid purification unit particularly adapted for home use in conjunction with low pressure water systems. The unit is adapted to receive water from a low pressure source to provide pure water that would otherwise be unobtainable for such purposes as drinking and direct all unpurified water to appliances within the home utilizing water without wastage.

United States Patent 91 Clark 1 REVERSE OSMOSIS SEPARATION APPARATUSInventor:

Assignee:

Filed:

Appl.

George B. Clark, Waukesha, Wis.

Aqua-Chem, Inc., Milwaukee, Wis.

March 30, 1970 US. Cl ..210/321, 210/433 Int. Cl. ..B01d 31/00 Field ofSearch ..210/22, 23, 321, 440, 491,

References Cited UNITED STATES PATENTS 4/1970 Kryzer ..210/321 X PrimaryExaminer-Frank A. Spear, Jr. Att0mey--Fred Wiviott and Ralph G.l-lohenfeldt [5 7] ABSTRACT A reverse osmosis liquid purification unitparticularly adapted for home use in conjunction with low pressure watersystems. The unit is adapted to receive water from a low pressure sourceto provide pure water that would otherwise be unobtainable for suchpurposes as drinking and direct all unpurified water to applianceswithin the home utilizing water without wastage.

13 Claims, 4 Drawing Figures I REVERSE OSMOSIS SEPARATION APPARATUSBACKGROUND OF THE INVENTION For many years, there has existed a need forrelatively inexpensive water purification equipment which may beemployed in homes or the like to provide relatively small quantities ofpure water for drinking purposes. The need is particularly great wherethe water supply to the home either by city distribution systems or froma well contains a great deal of minerals. In some cases, standard watersoftening systems have met the need. However, where minerals notparticularly susceptible to removal by standard water softeningoperations, such as sodium ions, chloride ions, sulfate ions, detergentsand poorly ionized organic pollutants are present, the need has not beensatisfied. And even standard water softening equipment has significantdrawbacks such as the relatively high cost of the equipment, continuingsalt requirements, maintenance, etc., with manually regeneratedsofteners further requiring periodic attention attendant toregeneration.

One phenomenon that may be employed to effect the removal of suchminerals is that of reverse osmosis wherein impure water is subjected toa pressure in excess of its osmotic pressure while in contact with asemipermeable membrane. The water that then permeates the membrane isrelatively pure and the instant invention makes use of this phenomenon.

Reverse osmosis purification equipment possesses significant advantagesover other systems in terms of cost of equipment, low maintenance costsand reliability.

While reverse osmosis water purification systems for home use have beenproposed, the same have been designed for essentially continuous waterflow across the membrane surface to reduce polarization effects(concentration buildup), at the membrane face which would result inprecipitation of solids causing deterioration in membrane performance.Further, that liquid which passes the membrane face and does notpermeate the membrane as product water is discharged to waste in orderto sustain flow thereby resulting in severe wastage of water. I

SUMMARY OF THE INVENTION It is the principal object of the invention toprovide a new and improved water purification device adapted for homeuse utilizing the principle of reverse osmosis.

More specifically, it is anobject to provide such a reverse osmosis unitthat can be used in conjunction with intermittently operated water linesand which will not restrict the flow of water to appliances in the home.

The exemplary embodiment of the inventionachieves the foregoingobjectives with the following construction. The reverse osmosis unit isintended to be placed in series with a source of water under pressureEach membrane cell is defined by a tubular, semipermeable membranereceived within and supported by a corresponding support tube. Accordingto one embodiment of the invention, the tubular membrane is cast on aporous carrier tube to form an integral membrane unit which is receivedwithin a support tube.

Water from the source passing through each membrane cell contacts oneside of the membrane therein and that water which permeates the membraneis directed to a pure water outlet which is in fluid comm unication withthe opposite side of the membrane, namely, with the interface betweenthe membrane and its support tube or, if a porous carrier tube is used,with the interface of the porous carrier tube and the support tube.

The plurality of support tubes have their ends received in respectiveheaders. Each header in turn includes an end cap with one of the endcaps including a channel therein for connecting the tubes in the desiredflow pattern. The other end cap includes similar channel means inaddition to the inlet and the outlet. One of the end caps is furtherprovided with a pure water outlet which is in fluid communication withthe interface between the tubular membrane and the support tube.According to one embodiment of the invention, each of the tubularmembrane units is provided with a liquid impervious end which extendsbeyond the end of its respective support tube. There is further provideda grooved surface in fluid communication with the interface of eachmembrane unit and its respective support tube and the grooved surface issealed from the end of the membrane by means of a sealing means in theform of a thin, flexible sheet having apertures which receive liquidimpervious ends of each membrane tube. Each aperture has the same shapeas the liquid impervious end of the associated membrane but is formedwith a significantly smaller cross sectional area. The resulting sealpermits easy insertion and removal of tubular membranes which haveserved their usefulness and yet provides a strong seal which tends toprovide increasingly better sealing engagement as system pressure isincreased.

Other objects and advantages will become apparent from the followingspecification taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS path employed in DESCRIPTION OF THEPREFERRED EMBODIMENT As best seen in FIG. 1, an exemplary embodiment ofthe invention is intended for use in a water system including a source10 of water under pressure.' The 'source 10 may be a city waterdistribution system or an ordinary well and pump combination. In anyevent, it is desirable that the source 10 provide low mineral contentwater to the system at a pressure generally within the range of 30-70psig. Also included in the system is a plurality of water utilizingappliances 12. As used herein, the term appliances means any device towhich water is supplied for a useful purpose. For example, theappliances 12 may take on the form of kitchen sinks, toilets, drinkingfountains, humidifying systems, bathtubs, etc.

A pipe 14 serves as an inlet conduit from the source and is connected bymeans of appropriate fittings, generally designated 16, to aconventional bypass valve 18 having a manual operator 20. Bypass valve18 also includes a connection via fittings 22 and a pipe 24 to theappliances 12. In addition, the bypass valve 18 is connected to aconduit 16 through which water from the source 10 may be directed to apurification unit, generally designated 28, and is connected to aconduit 30 from which water may be received from the unit 28 to bedirected through the conduit 24 to the appliances 12. As is well known,the operator of the bypass valve 18 may be selectively operated toeither direct water from the source 10 through the unit 28 and then tothe appliances 12, or, directly from the source 10 to the appliances 12.

The purification unit 28 includes a pair of spaced headers 32 and 34having associated end caps 36 and 38 respectively. Each of the headers32 and 34 has its respective end cap 36 and 38 secured thereto by anysuitable clamping means. According to one embodiment, conventional ringclamps 40 may be employed. Extending between the headers 32 and 34 are aplurality of membrane support tubes 42.

As seen in FIG. 1, the inlet conduit 26 is connected by means offittings 44 to an inlet in the end cap 36 while the conduit 30 isconnected to an outlet in the end cap 36 by means of fittings 46. Theend cap 36 is also provided with a small pure water outlet 48 which maybe connected by means of a flexible hose or the like to any suitablepure water collection means or utilization system.

Turning now to FIG. 2, the purification unit may be seen in greaterdetail. The headers 32 and 34 are generally similar and accordingly,only one need be described in detail. Specifically referring to theheader 32, the same includes a plurality of circular apertures 50 whichreceive the ends of the support tubes 42. According to one embodiment ofthe invention, the support tubes 42 may be arranged in the desiredconfiguration and the end caps 32 and 34 cast about the ends of themutilizing a suitable plastic. According to another embodiment of theinvention, the end caps 32 and 34 may be preformed and have the tubesmounted in the apertures 50 and secured thereto by means ofa suitableresin. The end cap 32 includes a recess 52 having a stepped outer lip54.

Received within the recess 52 is a baffle 56 which, as seen in FIGS. 2and 3, includes apertures 58 which are aligned with the apertures 50 inthe end cap. The baffle 56 also includes a plurality of baffle grooves60 in the innermost face thereof which interconnect each of theapertures 56 to a central collection point defined by a chamferredaperture 62 in the center of the baffle 56. Returning to FIG. 2, thechamferred aperture 62 receives a conduit 64 having a flared end 66 forretention purposes and which extends through a bore 67 in the end cap36. The conduit 64 serves as the pure water outlet 48.

The baffle 56 associated with the header 34 is similarly formed withbaffle grooves 60 and the chamferred aperture 62. However, in lieu ofthe conduit 64, a dead ended cap 68 is provided.

Wlthin each of the support tubes 42 is a membrane unit, generallydesignated 70, which consists essentially of an outer paper tube 72having a tubular semipermeable membrane 74 bonded to the interiorthereof. The ends of each unit are provided with plastic ferrules 76having tapered ends 78. Preferably, either the outer surface of thepaper tube 72 or the inner surface of the support tube 42 or both, isprovided with a plurality of thin, longitudinally extending grooves toenhance the flow of purified water permeating the membrane 74 and papertube 72 to the baffle grooves 60.

The foregoing construction of the membrane unit 70 and its cooperationwith grooves either in the paper tube 72 or in the support tube 42 orboth, is set forth in greater detail in the commonly assignedapplication of Clark, bearing Ser. No. 788,871, filed Jan. 3, 1969, andentitled Reverse Osmosis Liquid Purification", now Pat. No. 3,518,900,issued June l, 1971.

Since, as will be seen, purified water accumulates in the header 34which is remote from the outlet 48, provision is made to conduct suchpurified water to the same. Specifically, the centermost one of thesupport tubes 42, designated 80, is not provided with a membrane unit.Furthermore, the same is arranged in fluid communication with the bafflegrooves 60 in the baffle 56 associated with the header 34.

As a result of the foregoing construction, pure water permeating themembrane film 74 of each membrane cell will be conducted along theinterface of each membrane unit 70 and its corresponding support tube 42through the paper tube 72 and/or the longitudinally extending groovesmentioned previously to the baffle grooves 60 in both of the baffles 56.In the case of the baffle 56 associated with the header 32, purifiedwater will be directed by the baffle grooves 60 directly to the outlet48. In the case of the baffle 56 associated with the header 34, thebaffle grooves 60 will direct the purified water to the center tube 80of the unit 28 through which it may flow to the outlet 48.

Referring now to the end cap 36, it will be seen that the same isprovided with a plurality of redirecting channels 82 in fluid connectionwith the ends of the membrane units 70. Similarly, the end cap 38 isprovided with channels 84.

The end cap 36 is additionally provided with a fluid inlet and a fluidoutlet to be connected via the fittings 44 and 46 to the conduits 26 and30 respectively. In FIG. 2, the inlet is shown as a bore 86 in the endcap 36 while the outlet is not shown.

Each end cap 36 and 38 also includes a relatively shallow recess 90surrounded by an outwardly projecting ring flange 92 which in turn issurrounded by a stepped relieved portion 94. The outside diameter of thering flange 92 is equal to the inside diameter of the recess 52 of thecorresponding header while the outside diameter of the stepped portion94 is the same diameter as the inside diameter of the stepped flanged 54of the associated end cap. As a result, the ring flange 92 serves as aguide means to properly locate the end caps 36 and 38 with respect totheir corresponding headers 32 and 34 whilethe provision of the steppedportions 54 and 94 define a small recess which may receive an O-ring 96to seal the end caps to their respective headers.

In order to effectively minimize cross flow between the channels 82, agross seal in the form of a flexible gasket 98 is located in the recess90 of eachend cap and defines, with the associated baffle 56, a highpressure area 99. The gasket 98 includes a plurality of apertures 100having a diameter less than the outside diameter of the plastic ferrules76 and are arranged on the gasket 98 to be concentric with the supporttubes 42. Thus, as seen in FIG. 2, each ferrule extends partly into thegasket to provide a seal.

Finally, to seal the inlet water stream from the outlet water stream,there is provided a seal 102 bonded to the back side of each baffle 56within the high pressure area 99. The seal 102 is formed of a thin sheetof rubber and includes a plurality of apertures 104 (FIG. 3) throughwhich the ferrules 76 extend before engaging the gasket 98. Theapertures 104 have a smaller diameter than the outside diameter of eachferrule and each sheet forming the seal 102 has a greater diameter thanthe inside diameter of the recess 52 of the associated end cap.

Each seal 102 is located against the side of the baffle 56 opposite thegroove 60 and because of the relative dimensions set forth previously,the outer periphery of the same tends to form an upturned lip 106against the side of the recess 52 in the associated header 34 while theedges of the apertures 104 form upturned lips 108 about the associatedplastic ferrule 76. The inherent resiliency of the material forming eachseal 102 insures sealing engagement between the baffle 56, the ferrule76 and the associated header. Furthermore, because of the directionofthe upturned lips 106 and 108 and their location on the high pressureside of the system, it will be appreciated that increased systempressure will tend to push the upturned portions 106 and 108increasingly harder against the end cap and the ferrule, respectively.Accordingly, there is provided a seal whose effectiveness increases aspressure increases.

The usefulness of the seals 102 is not limited to low pressure reverseosmosis operating conditions but may be employed with advantage inreverse osmosis apparatus operating at extremely high pressures such as1,000 psig.

Furthermore, each seal 102 need not be formed separately from the baffle56 but may be cast integrally thereon. When the reverse osmosisapparatus operates at relatively low pressure, the entire baffle 56 insea] 102 may be formed as a single unit out of soft rubber. However, ifthe apparatus will operate at high pressures, total formation of softrubber ofa combined baffle 56 and seal 102 may not be desirable due tothe high pressure applied to the backside of the baffle having atendency to collapse the grooves therein. Therefore, the grooved side ofthe baffle is preferably formed of a hard rubber while the seal portion102 of such construction would be formed ofa soft rubber.

Additionally, the seal 102, whether fabricated separately from thebaffle 56 or integrally therewith, need not be formed of rubber. Thereare varieties of suitable plastics having the requisite flexibility soas to render their use satisfactory. However, practice has shown that arubber material is somewhat desirable in that tolerances in forming andlocating the apertures in the seal 102 need not be as exacting as wouldbe the case if plastics were used.

Referring now to FIG. 4, an exemplary flow pattern is illustrated.According to one embodiment of the invention, 19 of the tubes 42 areprovided with the centermost tube being utilized as the return conduitfor the purified water and the remaining 18 tubes serving as supporttubes for membrane structures 70. The 18 tubes are grouped into sixgroups of three each and the channels 82 and 84 are constructed so thateach group of three tubes is in series with the remaining groups oftubes while the tubes in each group are in parallel with each other.Obviously, other arrangements can be used. However, it is desirable thatat least some of the tubes be connected in parallel so as not torestrict the flow of water through the unit to the appliances 12.

In operation, water at line pressure, generally on the order of 30-70psig is fed into the unit and, for most water supplies of the type withwhich the invention is concerned, such a pressure will be in excess ofthe osmotic pressure of the inlet water. Accordingly, reverse osmosiswill take place with pure water being directed through the outlet 48whether or not the appliances 12 are being used at that time, because ofthe presence of pressurized water within the unit reverse osmosis willcontinue to take place. When the appliances 12 are used, there will beflow through the unit to the appliances 12, which flow will not berestricted due to the use of the parallel arrangement of the membranecells mentioned previously. Furthermore, the flow of water through theunit to appliances requiring a relatively large quantity of water, suchas a toilet or a bathtub occurs will have the effect of flushing thesurfaces of the membranes to preclude buildup of unwanted material whichwould otherwise effect the puriflcation rate of the membrane.

It will therefore be appreciated that the invention provides a low cost,low maintenance means for providing relatively pure water for suchpurposes as may be desired in a way that all water directed to the unitand not purified thereby may be utilized without wastage.

lclaim:

1. In a water purifying system, the combination comprising:

inlet means adapted to be connected to a source of pressurized feedwaterand outlet means adapted to be connected to feedwater utilizingappliance means,

tubular reverse osmosis water purifying means constructed and arrangedto allow substantial flushing flow inside the tubes and interposedbetween said inlet and outlet means and connected serially between afeedwater source and appliance means, a pure water outlet, saidpurifying means comprising semipermeable membrane means having one sidethereof in fluid communication with said inlet means and another side influid communication with said pure water outlet, said appliance feedingoutlet being in fluid communication with said one side of said membranefor receiving all water from said feedwater inlet not permeating saidmembrane and feeding the same to appliance means, the pressure appliedto said inlet being substantially the same as the pressure of thefeedwater source and the flow of feedwater through said inlet beingrelatively small when said appliance outlet is not conducting water andrelatively high to flush said purifying means of concentrated impuritieswhen said appliance outlet is conducting water.

2. The system of claim 1 further including a selectively operable bypassvalve interconnecting said inlet and said appliance feeding outlet.

3. The system of claim 1 wherein said membrane means comprises aplurality of membrane cells, at least some of said cells being connectedin parallel flow relation so as not to restrict the flow of water tosaid appliance means.

4. A reverse osmosis water purification unit adapted for use withchanging flow low pressure low mineral content water systems to providepure water without wastage of water comprising:

a plurality of membrane cells, at least some of which are connectedtogether for parallel flow of water therethrough and each including asemipermeable membrane having a first side to be subjected to impurewater and a second side from which pure water may be received, saidmembrane cells defining a closed flow path;

inlet means adapted to be connected with an impure water distributionsystem and being in fluid communication with said one sides of saidmembrane for receiving and directing all impure input water directlyfrom the water distribution system to said first side of said membranesand being located at one end of said flow path;

impure water outlet means in fluid communication I with said first sideof said membranes and located at the other end of said flow path, saidoutlet means being constructed and arranged to direct all water fromsaid inlet and passing through said flow path to a point of use, wherebyto provide high velocity flow in series with a system to flushconcentrated impurities from said membrane cells;

a pure water outlet in fluid communication with said second side of saidmembranes;

each of said membrane cells being tubular and comprising an innertubular semipermeable membrane and an outer support tube;

first header means supporting one end of each of the plurality of tubes;

second header means supporting the other end of each of the pluralityoftubes; I

first end cap means associated with one of said header means forconnecting certain of the tubes for parallel flow and other for serialflow;

and second end cap means associated with the other' of said header meansincluding said impure water inlet means and said impure water outletmeans; one of said end cap means further including said pure wateroutlet and means in fluid communication with the interface of each tubeand the corresponding membrane and said pure water outlet. 5. A reverseosmosis unit according to claim 4 wherein each tubular membrane includesa liquid impervious end located beyond an end of the respective supporttube and said means in fluid communication with the interface of eachtube and the corresponding membrane includes a grooved surface; andsealing means in sealing engagement with said liquid impervious ends toseal the same from said grooved surface.

6. A reverse osmosis unit according to claim 5 wherein said sealingmeans comprises a sheet of deformable material having a plurality ofapertures adapted to receive the liquid impervious ends of said tubularmembranes, the cross sectional area of said apertures beingsignificantly less than the cross sectional area of said liquidimpervious ends.

7. In a system for separating the solvent in a liquid mixture from themixture by reverse osmosis, the combination comprising:

a support tube for a semipermeable membrane,

a tubular membrane within said support tube,

one of said membrane and said support tube being provided with a liquidimpervious end,

a mounting arranged so that said liquid impervious end projects from thesame,

liquid mixture directing means for directing a liquid mixture under highpressure to the interior of said tubular membrane,

said directing means and said mounting defining a high pressure area,and

sealing means comprising a thin flexible, generally normally planarsheet-like means having an aperture similar in shape to the shape ofsaid liquid impervious end but of significantly smaller size disposedabout said liquid impervious end and having one side backed by saidmounting and another side facing said high pressure area and having anoutturned lip embracing said liquid impervious end within said highpressure area and formed by distortion of the aperture surrounding aportion of the sealing means when the same is applied to the liquidimpervious end to thereby provide a seal that responds positively toincreasing pressure in said high pressure area.

8. Reverse osmosis apparatus according to claim 7 wherein said liquidimpervious means is on the end of the tubular membrane.

9. A reverse osmosis apparatus according to claim 7 wherein saidmounting comprises a baffle having a groove in fluid communication withthe interface of said support tube and said tubular membrane.

10. In a system for separating the solvent in a liquid mixture from themixture by reverse osmosis, the combination comprising: a support tubefor a semipermeable membrane, a tubular membrane within said supporttube and having a liquid impervious end extending therefrom, a bafflehaving an aperture receiving said liquid impervious end, said bafflehaving a fluid conduit on one side thereof in fluid communication withthe interface of said support tube and said tubular membrane and anormally planar lip on the other side thereof surrounding said aperture,said lip projecting into said aperture and being adapted to be distortedby the liquid impervious end of the membrane when the same is placed inthe aperture to tightly embrace the same; and means defining a highpressure area adjacent said other side of said baffle including meansfor introducing a liquid mixture under high pressure into said liquidimpervious end.

11. In a reverse osmosis apparatus according to claim 10 wherein saidlip is integral with said baffle.

12. In a reverse osmosis apparatus according to claim 10 wherein saidlip is bonded to said baffle.

13. In an apparatus for separating the solvent from a liquid mixture byreverse osmosis, the combination comprising: the plurality of elongated,tubular membrane structures, each having a liquid impervious end,mounting means mounting the ends of said membrane structures, saidliquid impervious ends projecting outwardly from said mounting means:means defining a high pressure area adjacent said liquid impervious endsincluding means for directing the liquid mixture to be processed underhigh pressure into said liquid impervi-

1. In a water purifying system, the combination comprising: inlet meansadapted to be connected to a source of pressurized feedwater and outletmeans adapted to be connected to feedwater utilizing appliance means,tubular reverse osmosis water purIfying means constructed and arrangedto allow substantial flushing flow inside the tubes and interposedbetween said inlet and outlet means and connected serially between afeedwater source and appliance means, a pure water outlet, saidpurifying means comprising semipermeable membrane means having one sidethereof in fluid communication with said inlet means and another side influid communication with said pure water outlet, said appliance feedingoutlet being in fluid communication with said one side of said membranefor receiving all water from said feedwater inlet not permeating saidmembrane and feeding the same to appliance means, the pressure appliedto said inlet being substantially the same as the pressure of thefeedwater source and the flow of feedwater through said inlet beingrelatively small when said appliance outlet is not conducting water andrelatively high to flush said purifying means of concentrated impuritieswhen said appliance outlet is conducting water.
 1. In a water purifyingsystem, the combination comprising: inlet means adapted to be connectedto a source of pressurized feedwater and outlet means adapted to beconnected to feedwater utilizing appliance means, tubular reverseosmosis water purIfying means constructed and arranged to allowsubstantial flushing flow inside the tubes and interposed between saidinlet and outlet means and connected serially between a feedwater sourceand appliance means, a pure water outlet, said purifying meanscomprising semipermeable membrane means having one side thereof in fluidcommunication with said inlet means and another side in fluidcommunication with said pure water outlet, said appliance feeding outletbeing in fluid communication with said one side of said membrane forreceiving all water from said feedwater inlet not permeating saidmembrane and feeding the same to appliance means, the pressure appliedto said inlet being substantially the same as the pressure of thefeedwater source and the flow of feedwater through said inlet beingrelatively small when said appliance outlet is not conducting water andrelatively high to flush said purifying means of concentrated impuritieswhen said appliance outlet is conducting water.
 2. The system of claim 1further including a selectively operable bypass valve interconnectingsaid inlet and said appliance feeding outlet.
 3. The system of claim 1wherein said membrane means comprises a plurality of membrane cells, atleast some of said cells being connected in parallel flow relation so asnot to restrict the flow of water to said appliance means.
 4. A reverseosmosis water purification unit adapted for use with changing flow lowpressure low mineral content water systems to provide pure water withoutwastage of water comprising: a plurality of membrane cells, at leastsome of which are connected together for parallel flow of watertherethrough and each including a semipermeable membrane having a firstside to be subjected to impure water and a second side from which purewater may be received, said membrane cells defining a closed flow path;inlet means adapted to be connected with an impure water distributionsystem and being in fluid communication with said one sides of saidmembrane for receiving and directing all impure input water directlyfrom the water distribution system to said first side of said membranesand being located at one end of said flow path; impure water outletmeans in fluid communication with said first side of said membranes andlocated at the other end of said flow path, said outlet means beingconstructed and arranged to direct all water from said inlet and passingthrough said flow path to a point of use, whereby to provide highvelocity flow in series with a system to flush concentrated impuritiesfrom said membrane cells; a pure water outlet in fluid communicationwith said second side of said membranes; each of said membrane cellsbeing tubular and comprising an inner tubular semipermeable membrane andan outer support tube; first header means supporting one end of each ofthe plurality of tubes; second header means supporting the other end ofeach of the plurality of tubes; first end cap means associated with oneof said header means for connecting certain of the tubes for parallelflow and other for serial flow; and second end cap means associated withthe other of said header means including said impure water inlet meansand said impure water outlet means; one of said end cap means furtherincluding said pure water outlet and means in fluid communication withthe interface of each tube and the corresponding membrane and said purewater outlet.
 5. A reverse osmosis unit according to claim 4 whereineach tubular membrane includes a liquid impervious end located beyond anend of the respective support tube and said means in fluid communicationwith the interface of each tube and the corresponding membrane includesa grooved surface; and sealing means in sealing engagement with saidliquid impervious ends to seal the same from said grooved surface.
 6. Areverse osmosis unit according to claim 5 wherein said sealing meanscomprises a sheet of deformable material having a plurality of aperturesAdapted to receive the liquid impervious ends of said tubular membranes,the cross sectional area of said apertures being significantly less thanthe cross sectional area of said liquid impervious ends.
 7. In a systemfor separating the solvent in a liquid mixture from the mixture byreverse osmosis, the combination comprising: a support tube for asemipermeable membrane, a tubular membrane within said support tube, oneof said membrane and said support tube being provided with a liquidimpervious end, a mounting arranged so that said liquid impervious endprojects from the same, liquid mixture directing means for directing aliquid mixture under high pressure to the interior of said tubularmembrane, said directing means and said mounting defining a highpressure area, and sealing means comprising a thin flexible, generallynormally planar sheet-like means having an aperture similar in shape tothe shape of said liquid impervious end but of significantly smallersize disposed about said liquid impervious end and having one sidebacked by said mounting and another side facing said high pressure areaand having an outturned lip embracing said liquid impervious end withinsaid high pressure area and formed by distortion of the aperturesurrounding a portion of the sealing means when the same is applied tothe liquid impervious end to thereby provide a seal that respondspositively to increasing pressure in said high pressure area.
 8. Reverseosmosis apparatus according to claim 7 wherein said liquid imperviousmeans is on the end of the tubular membrane.
 9. A reverse osmosisapparatus according to claim 7 wherein said mounting comprises a bafflehaving a groove in fluid communication with the interface of saidsupport tube and said tubular membrane.
 10. In a system for separatingthe solvent in a liquid mixture from the mixture by reverse osmosis, thecombination comprising: a support tube for a semipermeable membrane, atubular membrane within said support tube and having a liquid imperviousend extending therefrom, a baffle having an aperture receiving saidliquid impervious end, said baffle having a fluid conduit on one sidethereof in fluid communication with the interface of said support tubeand said tubular membrane and a normally planar lip on the other sidethereof surrounding said aperture, said lip projecting into saidaperture and being adapted to be distorted by the liquid impervious endof the membrane when the same is placed in the aperture to tightlyembrace the same; and means defining a high pressure area adjacent saidother side of said baffle including means for introducing a liquidmixture under high pressure into said liquid impervious end.
 11. In areverse osmosis apparatus according to claim 10 wherein said lip isintegral with said baffle.
 12. In a reverse osmosis apparatus accordingto claim 10 wherein said lip is bonded to said baffle.